Here is a bit of information that may or may not be of interest to you in your search.
There are two places refered to as Carleton. The first is in the western part of PEI, not far from O'Leary, Bloomfield and Alberton parishes. If Michael was Roman Catholic, he may likely have been baptised at Bloomfield or the RC church in Foxley River also not far from Carleton.
The second community is actually Carleton Siding, now known as Borden Carleton, where the bridge arrives from New Brunswick. Sometimes, people mistakenly refer to it as Carleton. It is served by the RC church at Seven Mile Bay.
I suggest you sift through the www.islandregister.com website if you have not already done so. Do an "advanced search" using " " around your ancestor. Browse the family surnames that you are familiar with - Michael may be listed in his mother's family file.
5. THOMAS3 KELLY (RICHARD2, ?1) was born 1822 in County Queens, Ireland, and died 25 December 1908 in Foxley River, P.E.I.. He married MARIA WHELAN 20 January 1847 in Cascumpec Mission, P.E.I.. She was born 1823 in Ireland, and died 9 July 1887 in Foxley River, P.E.I.. iv. MICHAEL KELLY, b. 18 May 1851, Lot 11, Portage, P.E.I.; d. Gloucester, Mass., USA.
Scrolling down to #17 finds another Kelly with a child Michael born 1892.